SERPINA1 (Serpin Family A Member 1): SERPINA1 is a marker that indicates the activity of a key protease inhibitor in the body, also known as alpha-1-antitrypsin. Mainly produced in the liver, it plays a crucial role in protecting the lungs from neutrophil elastase. A deficiency in SERPINA1 can cause alpha-1-antitrypsin deficiency, a genetic disorder linked to lung conditions such as emphysema and COPD, as well as liver diseases. It is vital for preserving the balance of proteolytic activity in lung tissues.